Fluid flow restrictor



Sept. 7, 1965 A. J. TAYLOR FLUID FLOW RESTRICTOR Filed Jan. 16, 1962 INVENTOR. Amhony J. Taylor ATTORNEY United States Patent 3,204,663 FLUID FLUW RESTRICTOR Anthony J. Taylor, London, England, assignor to Bahcoek dz Wilcox, Limited, London, England, a company of Great Britain Filed Jan. '16, 1962, Ser. No. 166,629 2 Claims. (Cl. 138--4t)) The present invention relates in general to the construction and operation of tubular heat exchangers, and more particularly, to heat exchangers comprising a row of tubes connected in parallel to a common fluid supply header.

In a tubular heat exchanger of the character described, it is desirable to achieve suitable distribution of the total fluid flow among the different tubes and usually uniform distribution of the fluid. Hitherto, this has been achieved by inserting a ferrule or a thimble formed with a suitable aperture into the inlet end of at least one of the tubes to restrict the flow of fluid through the tube. In this Way the rates of flow in the different tubes can be regulated.

However, the insertion of ferrules or apertured thimbles into the ends of the tubes is only possible when access can be had to these tube ends. This can be done by providing individual hand-hole openings and cover plates in the header generally opposite the corresponding tube ends. The use of such tube access openings is, in many cases, difficult due to the limited access within the header in service. Replacement of corroded flow restrictors is therefore dificult in many cases Without removing the entire tube row and header. Furthermore, ferrules or thimbles are liable to prevent proper drainage of such tubes and the apertures therein, when of small size, are liable to become blocked.

The general object of the present invention is the provision of a tubular heat exchanger having improved tube fluid flow restricting means, and more specifically, a flow restrictor which does not require access through an associated header for its installation in or removal from a tube.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which a preferred embodiment of the invention is disclosed.

Of the drawing:

FIG. 1 is a sectional elevation of a heat exchanger header and associated tube row having one or more fluid flow restrictors positioned in each of the tubes; and

FIG. 2 is a transverse section taken on the line 2-2 of FIG. 1.

In the drawing, the invention is illustrated as used in a once-through forced flow steam generating unit of the character illustrated in US. Patent 2,962,005 and comprises an elongated header of circular cross-section having a row of transversely spaced parallel tubes 12, one end of which extends through a corresponding opening in the wall of the header ill and is welded thereto in any suitable manner. The header 10 may be a supply header receiving a supply of Water at one end thereof and distributing the same to a row of tubes 12 lining a boundary surface of the furnace chamber or a gas pass of the steam generating unit. Where such a boundary surface is vertically arranged, it is usually essential that 3,204,663 Patented Sept. 7, 1955 the fluid flow in all of the tubes in the row be in the same direction, i.e., avoiding downflow of fluid through some of the tubes and upfiow in others. Flow resistors insure unidirectional fluid flow. It is also important for proper distribution of the fluid between the various tubes to provide a sufficient pressure drop across the inlet ends of the tubes to insure the desired distribution of fluid therebetween.

In accordance with the invention, some or all of the tubes 12 in the row are provided with flow restrictors in the form of one or more studs 14 having integral heads 16 at one end of an elongated shank 18. Each of the studs has its shank fitting into and extending through an aperture 20 in the tube wall into the interior of the tube to a point close to the opposite side. The stud shank fits tightly into the aperture 20. The stud head 16 contacts with and is Welded to the exterior of the tube, as indicated at 22. By providing two or more studs of the character described aligned in a single tube, as shown in FIG. 1, the resistance to fluid flow of the stud restrictors can be increased, but the constriction in the flow area will remain the same. The resistance to fluid flow of the restrictors can be varied by changing the length of the stud shank and thereby the extent of its projection into the interior of the tube or by varying the cross-sectional area of the stud shank or by varying both of these dimensions.

Stud restrictors of the character described can be used in any part of the fluid flow circuit where no change in state of the fluid tends to occur. However, where a change of state occurs, as in a steam generating tube, for example, it would be preferable to position the restrictors in the tube portions 20 adjacent the tube inlet header.

While in accordance with the provisions of the statutes I have illustrated and described herein a specific form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. In a system for distributing a liquid from a normally inaccessible supply header among a plurality of tubes connected thereto, flow restriction means disposed in at least some of said tubes, the latter tubes having formed an opening in the wall thereof adjacent the liquid inlet end thereof, said flow restriction means including a unitary fixed-position stud member having a cylindrical shank portion extending through said opening and diametrically across the flow area of the tube to a position close to but terminating short of the opposite side thereof, said shank portion occupying a substantial portion of the flow area of the tube, and an integral head portion larger in crosssection than said opening and seal-welded to the exterior of the tube.

2. In a high pressure system for distributing boiler feedwater from a normally inaccessible supply header among a plurality of parallel-flow tubes lining a boiler heating chamber, flow restriction means disposed in at least some of said tubes, the latter tubes having formed an opening in the wall thereof adjacent the liquid inlet end thereof, said flow restriction means including a unitary fixed-position stud member having a cylindrical shank portion extending through said opening and diametrical- 1y across the flow area of the tube to a position close to but terminating short of the opposite side thereof, said shank portion occupying a substantial portion of the flow area of the tube, and an integral head portion larger in cross-section than said opening and seal-Welded to the 5 exterior of the tube.

References Cited by the Examiner UNITED STATES PATENTS Simpson et al 138-46 X Shaw 2S7262.15

Keller W 13846 X Sorensen 165179 Shrode 137-561.1

Deverall 13756l.1

Nairnan 13756l.1

LEWIS J. LENNY, Primary Examiner.

8/87 Gillespie 5 10 EDWARD V. BENHAM, Examiner. 

1. IN A SYSTEM FOR DISTRIBUTING A LIQUID FROM A NORMALLY INACCESSIBLE SUPPLY HEADER AMONG A PLURALITY OF TUBES CONNECTED THERETO, FLOW RESTRICTION MEANS DISPOSED IN AT LEAST SOME OF SAID TUBES, THE LATTER TUBES HAVING FORMED AN OPENING IN THE WALL THEREOF ADJACENT THE LIQUID INLET END THEREOF, SAID FLOW RESTRICTION MEANS INCLUDING A UNITARY FIXED-POSITION STUD MEMBER HAVING A CYLINDRICAL SHANK PORTION EXTENDING THROUGH SAID OPENING AND DIAMETRICALLY ACROSS THE FLOW AREA OF THE TUBE TO A POSITION CLOSE TO BUT TERMINATING SHORT OF THE OPPOSITE SIDE THEREOF, SAID SHANK PORTION OCCUPYING A SUBSTANTIAL PORTION OF THE FLOW AREA OF THE TUBE, AND INTEGRAL HEAD PORTION LARGER IN CROSSSECTION THAN SAID OPENING AND SEAL-WELDED TO THE EXTERIOR OF THE TUBE. 